No, that isn't required. I have a 120 gallon tank that is tempered glass. You can set up a constant level siphon. That is what I have in that tank. It work like a siphon draining to a drain trap. The drain trap sets the level the system will overflow to. The part that goes into the tank siphons the water over the side to the drain trap.

Here is what a small one looks like:


The one in my 120 is made from 1" pipe. I added a top vent to that with a valve and some tubing so I can vent it if needed.